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United States Patent | 6,103,986 |
Asakawa ,   et al. | August 15, 2000 |
A U-shaped magnetic plate is positioned on the side of a movable contact shoe opposite to a fixed contact shoe, and the tips of the respective legs of the magnetic plate face via a gap the movable contact shoe in a closed condition of the movable contact shoe. A magnetic plate is attached to the surface of the movable contact shoe at the side of the fixed contact, so that the magnetic plates form a closed magnetic circuit surrounding the movable contact shoe. If a high current, such as short circuit current, flows, a magnetic flux passing through the closed magnetic circuit induces an attractive force between the upper end surfaces of the U-shaper magnetic plate and the end surface of the magnetic plate. Accordingly, the movable contact shoe is rapidly opened to quickly interrupt the current, before a signal from an overcurrent trip apparatus operates an opening and closing mechanism. The opening speed of the movable contact shoe is increased when high current flows.
Inventors: | Asakawa; Koji (Saitama, JP); Fujihira; Takumi (Saitama, JP); Uchida; Naoshi (Saitama, JP); Kuboyama; Katsunori (Saitama, JP); Takahashi; Tatsunori (Saitama, JP); Toyama; Kentaro (Saitama, JP) |
Assignee: | Fuji Electric Co., Ltd. (Kawasaki, JP) |
Appl. No.: | 272290 |
Filed: | March 19, 1999 |
Apr 07, 1998[JP] | 10-111502 |
Current U.S. Class: | 218/22; 218/27; 218/31; 218/32; 218/36; 335/16; 335/195 |
Intern'l Class: | H01H 033/18; H01H 075/02 |
Field of Search: | 218/16,17,18,19,20,22,24,26,30,31,32,36,40,146,148-149,154-158,27 335/16,147,201,195,202 |
4132968 | Jan., 1979 | Lang | 335/16. |
4367448 | Jan., 1983 | Nishizako | 335/201. |
4743720 | May., 1988 | Takeuchi et al. | 335/201. |
5493091 | Feb., 1996 | Devautour et al. | 218/30. |
5495083 | Feb., 1996 | Aymami-Pala et al. | 218/1. |
5548258 | Aug., 1996 | Kuboyama et al. | 218/22. |
5569894 | Oct., 1996 | Uchida et al. | 218/27. |
5589672 | Dec., 1996 | Uchida et al. | 218/34. |
5815058 | Sep., 1998 | Gizaw | 218/22. |
5834724 | Nov., 1998 | Asakawa et al. | 218/36. |